The present invention relates to a method of adjusting and/or correcting the impact energy of a letter key or type element of a typewriter, printer or the like printing machine, and also to the typewriter, printer and/or other printing machine which uses that method.
A printing machine is known, in which a type element or letter key is pressed against a substrate by a hammer accelerated by a hammer electromagnet. The hammer flight time determines the magnitude of the impact energy and the duration of current flow in the hammer electromagnet is adjusted according to that.
It is important that the impact of the letter key or the type element on the substrate, e.g. a paper guided around a typewriter roll, occurs with a definite predetermined impact energy, so that a uniform type character with sufficiently strong impression results, while avoiding damage to the substrate.
The impact energy of the key or type element is proportional to the square of the speed at the moment of impact. The impact speed of the type element and/or the hammer is produced because the hammer electromagnet accelerates the hammer with a certain current level flow through the electromagnet for a predetermined current flow duration. After this acceleration stage, a motion stage occurs without acceleration, in which the hammer up to the time of impact moves toward the type element and/or the substrate with a uniform speed. Since the geometric relationships and dimensions, i.e. especially the path of the hammer to impact, remain the same, the free flight time is directly proportional to the free flight speed and produces accordingly a certain impact energy.
Conventionally the free flight speed of the hammer is measured in production of the typewriter or printer with different measuring methods and is stored in the data memory of the central data processing unit of the typewriter or printer, so that, when a certain type element or letter key is activated, an appropriate current flow duration results, which leads to the desired impact energy.
Determination of a certain current flow duration in advance for the hammer electromagnet for a certain type element has not previously taken into account variations in the impact conditions due to manufacturing conditions and changes with increasing operating time.